<html>
<head><meta charset="utf-8"><title>const fn survey · t-libs · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/index.html">t-libs</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html">const fn survey</a></h3>

<hr>

<base href="https://rust-lang.zulipchat.com">

<head><link href="https://rust-lang.github.io/zulip_archive/style.css" rel="stylesheet"></head>

<a name="209587761"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209587761" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> pickfire <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209587761">(Sep 10 2020 at 01:27)</a>:</h4>
<p>There have been frequent misunderstanding for <code>const fn</code> which <span class="user-mention" data-user-id="120791">@RalfJ</span> have been receiving every month IIRC. People (including myself) thought that using <code>const fn</code> is able to allow the compiler to optimize the binary better but it was just to allow using functions to assign to <code>const</code>. What do you all think? Should we start a survey so we know others understanding and if possible figure out how to solve the misunderstanding?</p>



<a name="209588285"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209588285" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209588285">(Sep 10 2020 at 01:40)</a>:</h4>
<p>I don't see how a survey would help clear up confusion - more, better documentation. We could add an item to the library guidelines. I suspect it's mostly not a libs concern though? It feels lang-y.</p>



<a name="209595060"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209595060" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209595060">(Sep 10 2020 at 04:32)</a>:</h4>
<p>If it's assigning to <code>const</code> isn't the compiler then doing constant propagation?</p>



<a name="209595306"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209595306" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jubilee <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209595306">(Sep 10 2020 at 04:39)</a>:</h4>
<p>"constant propagation" in most Rust discussion contexts usually references implicit constant folding done at compile time without specific request to the compiler.<br>
What is done when a <code>const</code> is assigned-to with a non-immediate value is sometimes  referred to as "compile-time function evaluation".</p>



<a name="209601255"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209601255" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Lokathor <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209601255">(Sep 10 2020 at 06:49)</a>:</h4>
<p>I think the key point of common confusion here is that <em>outside of a const declaration</em> the compiler can compile-time evaluate, or not evaluate, any expression it chooses. Only a const declaration <em>forces</em> the compile-time evaluation.</p>
<p>And <em>outside of a const declaration</em> it doesn't matter if a function call is to a <code>fn</code> or a <code>const fn</code>, the call might or might not be compile-time evaluated by the whim of the optimizer.</p>



<a name="209601738"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209601738" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> RalfJ <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209601738">(Sep 10 2020 at 06:57)</a>:</h4>
<p>Yeah, I don't think a survey would help here. Better docs and maybe some blog posts might.</p>



<a name="209630642"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209630642" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209630642">(Sep 10 2020 at 12:28)</a>:</h4>
<p><span class="user-mention silent" data-user-id="281757">Jubilee</span> <a href="#narrow/stream/219381-t-libs/topic/const.20fn.20survey/near/209595306">said</a>:</p>
<blockquote>
<p>"constant propagation" in most Rust discussion contexts usually references implicit constant folding done at compile time without specific request to the compiler.<br>
What is done when a <code>const</code> is assigned-to with a non-immediate value is sometimes  referred to as "compile-time function evaluation".</p>
</blockquote>
<p>Would you care to elaborate on the differences between implicit constant folding and compile-time function evaluation in the Rust compiler context?</p>



<a name="209631100"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209631100" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209631100">(Sep 10 2020 at 12:33)</a>:</h4>
<p>I'm curious where all of this happens in the code.</p>



<a name="209631547"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209631547" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lzutao <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209631547">(Sep 10 2020 at 12:36)</a>:</h4>
<blockquote>
<p>Would you care to elaborate on the differences between implicit constant folding and compile-time function evaluation in the Rust compiler context?</p>
</blockquote>
<p>I think one is guarantee and other is not.</p>



<a name="209631972"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209631972" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209631972">(Sep 10 2020 at 12:40)</a>:</h4>
<p>Right, so is the compiler actually sorting that out for functions or not? In theory it would.</p>



<a name="209632237"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209632237" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jubilee <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209632237">(Sep 10 2020 at 12:41)</a>:</h4>
<p>Correct.<br>
In CTFE, any nontrivial CTFE is is an attempted execution by the built-in interpreter, miri, I believe? And if it fails, that is returned to the programmer as an error. In implicit constant folding, a few different things can happen. I believe miri and the const-eval infrastructure in general can nudge that along, but also LLVM is capable of doing constant folding on its own.</p>



<a name="209634116"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209634116" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209634116">(Sep 10 2020 at 12:56)</a>:</h4>
<p>I agree that a blog post on this would be fascinating.</p>



<a name="209671210"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209671210" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> pickfire <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209671210">(Sep 10 2020 at 16:18)</a>:</h4>
<p><span class="user-mention" data-user-id="281739">@Oliver</span> Heh, sounds like I successfully found others like me here.</p>



<a name="209671376"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209671376" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> pickfire <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209671376">(Sep 10 2020 at 16:19)</a>:</h4>
<p><span class="user-mention" data-user-id="120791">@RalfJ</span> I fell like just posting it here even helped someone like <span class="user-mention" data-user-id="281739">@Oliver</span>. Maybe every time we post something regarding to <code>const fn</code> we should always put this as a note, <code>const fn</code> is not for optimization like others think, it is just allowing the function to be runned in a <code>const</code> variable context.</p>



<a name="209671588"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209671588" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> pickfire <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209671588">(Sep 10 2020 at 16:21)</a>:</h4>
<p>Yes, blog posted definitely works better than survey. <span class="user-mention" data-user-id="120791">@RalfJ</span> mentioned that he was interested in writing a blog regarding this but he have a few other blog posts in mind before this.</p>



<a name="209676356"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209676356" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Lokathor <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209676356">(Sep 10 2020 at 16:54)</a>:</h4>
<p>I'm not even sure what would go in a blog post about this to make it fascinating.</p>



<a name="209684515"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209684515" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209684515">(Sep 10 2020 at 17:57)</a>:</h4>
<p>A technical summary of constant propagation. Maybe more enlightening than fascinating but that depends on the reader, I'm easily impressed I guess :P</p>



<a name="209684605"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209684605" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209684605">(Sep 10 2020 at 17:57)</a>:</h4>
<p>Well there is already this of course: <a href="https://rustc-dev-guide.rust-lang.org/borrow_check/region_inference/constraint_propagation.html">https://rustc-dev-guide.rust-lang.org/borrow_check/region_inference/constraint_propagation.html</a></p>



<a name="209685198"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209685198" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209685198">(Sep 10 2020 at 18:01)</a>:</h4>
<p>So for CTFE maybe it's equally suited to beings a dev-docs addition as it is to a blog, to be fair to everyone here my coverage of the existing literature is in the lowest percentile</p>



<a name="209687355"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209687355" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209687355">(Sep 10 2020 at 18:16)</a>:</h4>
<p>Like I didn't know constant propagation was documented until just now</p>



<a name="209755490"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209755490" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> RalfJ <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209755490">(Sep 11 2020 at 08:56)</a>:</h4>
<p><span class="user-mention silent" data-user-id="281739">Oliver</span> <a href="#narrow/stream/219381-t-libs/topic/const.20fn.20survey/near/209684605">said</a>:</p>
<blockquote>
<p>Well there is already this of course: <a href="https://rustc-dev-guide.rust-lang.org/borrow_check/region_inference/constraint_propagation.html">https://rustc-dev-guide.rust-lang.org/borrow_check/region_inference/constraint_propagation.html</a></p>
</blockquote>
<p>constraint propagation and constant propagation have basically nothing to do with each other besides being spelled similar ;)</p>



<a name="209778841"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209778841" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209778841">(Sep 11 2020 at 13:15)</a>:</h4>
<p>Oof :)</p>



<a name="209779012"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209779012" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209779012">(Sep 11 2020 at 13:16)</a>:</h4>
<p>Tl;DR bites back</p>



<a name="209779129"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209779129" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> DPC <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209779129">(Sep 11 2020 at 13:17)</a>:</h4>
<p>i don't blame you Oliver, i had to read Ralf's message a couple of times to realise it wasn't a "X and X are two different things" <span aria-label="grinning" class="emoji emoji-1f600" role="img" title="grinning">:grinning:</span></p>



<a name="209785883"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209785883" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> RalfJ <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209785883">(Sep 11 2020 at 14:16)</a>:</h4>
<p>yeah those two words do look rather similar^^</p>



<a name="209799155"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209799155" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> pickfire <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209799155">(Sep 11 2020 at 15:56)</a>:</h4>
<p>Someone did a post already <a href="https://www.reddit.com/r/rust/comments/iksmgk/psa_what_is_const_fn/">https://www.reddit.com/r/rust/comments/iksmgk/psa_what_is_const_fn/</a>, but it didn't mention specifically that <code>const fn</code> does not help improving compilation performance, still it should already clarify stuff a bit.</p>



<a name="209811931"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209811931" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209811931">(Sep 11 2020 at 17:40)</a>:</h4>
<p>It's isn't optimized because the work is being done in LLVM/has already been lowered to LLVM?</p>



<a name="209813264"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209813264" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Lokathor <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209813264">(Sep 11 2020 at 17:51)</a>:</h4>
<p>it has no automatic optimization difference.</p>



<a name="209829362"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209829362" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> RalfJ <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209829362">(Sep 11 2020 at 20:11)</a>:</h4>
<p>(and it hasn't been demonstrated to be useful as an optimization clue -- not even C++ uses it, beyond it being an "inline" hint)</p>



<a name="209886279"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209886279" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209886279">(Sep 12 2020 at 15:37)</a>:</h4>
<p>So you are saying that in practice CTFE involves a code expansion (inlining - which does happens) but not a reduction to something actually treated as one might expect of a constant?</p>



<a name="209889500"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209889500" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oliver <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209889500">(Sep 12 2020 at 16:45)</a>:</h4>
<p>Oh well I just found this: <a href="#narrow/stream/146212-t-compiler.2Fconst-eval/topic/.22const.20or.20bail.20to.20dynamic.22.20possible.3F/near/209761074">https://rust-lang.zulipchat.com/#narrow/stream/146212-t-compiler.2Fconst-eval/topic/.22const.20or.20bail.20to.20dynamic.22.20possible.3F/near/209761074</a></p>



<a name="209927971"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209927971" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> RalfJ <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209927971">(Sep 13 2020 at 12:06)</a>:</h4>
<p><span class="user-mention silent" data-user-id="281739">Oliver</span> <a href="#narrow/stream/219381-t-libs/topic/const.20fn.20survey/near/209886279">said</a>:</p>
<blockquote>
<p>So you are saying that in practice CTFE involves a code expansion (inlining - which does happens) but not a reduction to something actually treated as one might expect of a constant?</p>
</blockquote>
<p>no, CTFE involves nothing of the sort. we have an interpreter that can evaluate MIR code directly.</p>



<a name="209927986"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/219381-t-libs/topic/const%20fn%20survey/near/209927986" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> RalfJ <a href="https://rust-lang.github.io/zulip_archive/stream/219381-t-libs/topic/const.20fn.20survey.html#209927986">(Sep 13 2020 at 12:07)</a>:</h4>
<p><a href="https://rustc-dev-guide.rust-lang.org/const-eval.html">https://rustc-dev-guide.rust-lang.org/const-eval.html</a> has some more detail</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
</html>